Department of Radiology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
Pediatr Radiol. 2013 Sep;43(9):1103-7. doi: 10.1007/s00247-013-2660-y. Epub 2013 Apr 11.
The term "radiopaque" is commonly used when discussing foreign bodies and lists of radiopaque and non-radiopaque materials are sometimes created, but radiopacity is not a binary concept. A more fundamental understanding of radiopacity is necessary for the work-up of foreign bodies.
To demonstrate that "radiopaque" is a relative term.
Twenty foreign bodies of various sizes, shapes and materials were placed in a basin. Radiographs were obtained of the objects with 0, 2.5, 5 and 10 cm depth of water in the basin to simulate the appearance of a foreign body in human tissue. The progressively changing appearance of the objects was observed.
All of the objects were radiographically visible in the empty basin. Different objects demonstrated different appearances when immersed in progressively deeper levels of water, illustrating the effect of the surrounding water as well as the effects of object shape, size, orientation and composition.
The concept of radiopacity seems simple and the term "radiopaque" is sometimes used to describe an all or none phenomenon. However, radiopacity is a comparative concept implying relative X-ray attenuation. Accurate understanding of the radiographic appearance of foreign bodies requires one to keep in mind the concepts of relative X-ray attenuation and contrast resolution.
在讨论异物时，通常会使用“不透射线的”一词，并且有时会列出不透射线和非不透射线材料的清单，但射线不透明度不是一个二元概念。为了对外来异物进行评估，有必要更深入地了解射线不透明度。
证明“不透射线的”是一个相对的术语。
将二十个大小、形状和材质各异的异物放置在一个盆中。对盆中的物体分别进行 0、2.5、5 和 10 厘米深度的水的射线照相，以模拟异物在人体组织中的外观。观察物体逐渐变化的外观。
在空盆中，所有物体在射线照相中均可见。当物体浸入逐渐变深的水中时，不同的物体表现出不同的外观，这说明了周围水的影响以及物体形状、大小、方向和组成的影响。
射线不透明度的概念似乎很简单，并且有时会使用“不透射线的”一词来描述全有或全无的现象。然而，射线不透明度是一个相对的概念，意味着相对 X 射线衰减。准确理解异物的射线照相外观需要牢记相对 X 射线衰减和对比分辨率的概念。
